InnoTrans 2022 (31)

Another vehicle with alternative drive on Stadler's display was a unit referred by the manufacturer as an IPEMU (Independently Powered Electric Multiple Unit), in this case capable of running on batteries beyond the electrified networks. However, we will stick here to the internationally more widely used term BEMU (Battery Electric Multiple Unit).

This is a four-car Class 777 for the Merseyrail network of suburban lines in the Liverpool/Birkenhead conurbation. For this network, named after the Mersey river, Merseytravel has ordered 46 electric and 7 dual-mode trains. Their numbering distinguishes the type of propulsion, EMUs being Class 777/0s and BEMUs being Class 777/1s.

The Berlin exhibit 777 140 is thus the fortieth Class 777 unit for Merseyrail and simultanously the first batch-built Class 777 BEMU. We refer to this battery unit as the first production one because in 2021, a prototype battery system together with battery cooling was fitted under the floor of 777 002 to test the feasibility of the concept. Based on the positive test results, the customer then confirmed that it would like to deliver seven units from the ordered batch as BEMUs.

Stadler subsequently worked on the final design, which has higher capacity batteries compared to the prototype, and the battery cooling is located on the roof instead of under the floor. These differences are also the reason why the battery bay was removed from the 777 002 and this unit returned to the EMU version. The dual-mode 777s are designated with even numbers 777 142, 144, 146, 148, 150 and 152 .

The motivation for this design was the expansion of the Merseyrail network, with the perspective of extending third rail beyond the already electrified sections being described as almost non-existent, with reference to the high cost, thus the use of BEMUs will reduce the need to switch to diesel trains; at the moment, this is a section to the newly built Headbolt Lane station in the Kirkby area of north-east Liverpool, where Class 777 BEMUs will go on extended Nothern line services.

The traction batteries on these units are of the LTO-NMC (Lithium Titanate - Nickel, Manganese, Cobalt, the elements used in the electrodes) with a 320 kWh capacity and a 386 V nominal voltage. They are located under the floor of the front cars behind the outer bogies and are liquid cooled with the radiators located on the roof. The piping of the cooling circuit passes invisibly under the covers of the entrance door frames. The batteries take less than 15 minutes to recharge and have an expected life of at least 8 years. At a speed of 80 km/h and with fully charged batteries, the operation range of the train is 55 km.

The length of the train is 64 980 mm over couplings, the bodyshell width is 2,280 mm, the height 3,828 mm above rail top and the axle-load is 16.9 t. The bodies are welded from extruded aluminium profiles, the floor is 960 mm above rail top. The axle arrangement is 2' (Bo)' (Bo)' (Bo)' 2', with the powered Jakobs bogies. Each unit has a traction power of 2,100 kW (6 x 350 kW) and a starting acceleration of 1.1 m/s². The maximum speed when fed from the third rail is 120 km/h, in the battery mode 100 km/h.

For this project, Stadler has developed new bogies with the internal frame and with air suspension. For the future electrification of the lines around the Merseyrail network with 25 kV 50 Hz, all Class 777s can be retrofitted later, as well as being prepared for the ETCS OBU installation.

The trains have 184 seats and space for 302 standing passengers at a density of 4/m². The end cars have one 1,600 mm wide double-leaf sliding entrance doors on each sidewall and the intermediate cars have two pairs of doors. Automatically extending platforms are installed in the thresholds of all entrance doors to bridge the gap between the train and the platform. The interior is air-conditioned. There are evacuation doors at the fronts of the end cars, with retractable steps for exiting onto the track. In addition, Stadler has applied a patented system for the possibility of using the emergency exit to enable "bridging" to an adjacent unit.

The order for the Class 777 also includes maintenance of the trains for 35 years, and an option for up to 60 additional four-car sets. Production is split between the Szolnok (bodyshells), Albuixech (bogies) and Swiss and Polish works for final assembly: initially Altenrhein, followed by the new St. Margrethen facility (even units starting with 777 004), and Siedlce (odd units starting with 777 005). Currently 17 EMUs have been delivered to Liverpool, with eight completed trains awaiting delivery in Switzerland and 19 in Poland. A further eight sets are in various stages of production in Siedlce.

This waiting of finished trains is due to the ongoing modifications to the Merseyrail network, which are necessary mainly on account of the length of the Class 777s which is greater compared to the current Class 507 and 508 three-car trains. This is mainly related to the lengthening of platforms or moving of signals and signal sections, but also to modifications for wheelchair access. The Class 777 is expected to enter service probably in May 2023, the BEMU version only after the completion of the above mentioned Headbolt Lane station, where these units will run off the network equipped with a third rail.

Testing and approval of the battery version is currently underway at PCW, and the photo taken there shows the Berlin exhibit 777 140 on the track with third rail. This unit is envisaged for delivery to Liverpool in December 2022, with the remaining BEMUs to be delivered between February and May 2023.